In many TCP/IP networks, one or more routers use the Open Shortest Path First (OSPF) routing protocol to generate routing tables for each router. Such routing tables enable each router to deliver data to other routers and nodes (e.g., end terminal computing devices) throughout the network. Each router in the network may have one or more links that connect to other routers or nodes. Further, each router generates periodic messages known as link state advertisements (LSAs) that are provided to other routers in the network. Typically, each such periodic LSA provides information regarding the state of each of the links of the router that generated that particular periodic LSA. Further, when a link of a router faults (e.g., due to malfunction, disconnection, etc.), the router typically generates an event-driven LSA to be sent to the other routers in the network. Based on the receipt of the periodic LSAs and the event-driven LSAs, each router may implement a shortest path algorithm (e.g., Dijkstra's algorithm) to determine a shortest route from that router to every other router or node in the network.
In a typical implementation, periodic LSAs are provided by a router to every other router in the network every 30 minutes. If a first router does not receive a periodic LSA for a period of 60 minutes from a second router in the network, the first router typically updates its routing table to indicate the second router is down (e.g., malfunctioning, disconnected, etc.). The transmission of periodic LSAs congests the network with overhead messaging, which by definition is messaging that is used for overhead (i.e., administrative) tasks such as control and management of the network as opposed to substantive traffic communication between nodes. Thus, congestion due to overhead messaging reduces the effective bandwidth (i.e., throughput) of the network. The Internet Engineering Task Force (IETF) published Request for Comments No. 1793 (RFC 1793) on the topic of reducing the transmission of periodic LSAs in a network. One aspect of RFC 1793 involves designating an LSA as Do-Not-Age (DNA). LSAs that are designated as DNA do not age and therefore do not need to be periodically refreshed, thus reducing overhead messaging in the network and improving the effective bandwidth (i.e., throughput) of the network.
Event-driven LSAs can also cause (or at least contribute to) congestion in a network as a result of links, nodes, and/or routers in the network faulting due to malfunctions, due to management operations by a network operator (e.g., via a network control center/network management system (NCC/NMS)), and/or due to one or more other causes. Such management operations may include reconfiguring (e.g., setting up and tearing down) links on a node or router or conducting maintenance (that often involves powering down routers, nodes or links), as just a few examples. Such events may occur relatively often, thereby triggering the generation of a significant number of event-driven LSAs; as discussed above, this congests the network, and reduces the effective bandwidth (i.e., throughput) of the network.
Accordingly, there is a need for systems, methods, and devices for reducing overhead messaging, such as event-driven LSAs, in networks.
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the disclosed embodiments, so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.